How to use the pyvera.CATEGORY_POWER_METER function in pyvera

RESPONSE_SDATA = {
    "scenes": [{"id": SCENE1_ID, "name": "scene1", "active": 0, "root": 0}],
    "temperature": 23,
    "categories": [
        {"name": "Dimmable Switch", "id": CATEGORY_DIMMER},
        {"name": "On/Off Switch", "id": CATEGORY_SWITCH},
        {"name": "Sensor", "id": CATEGORY_ARMABLE},
        {"name": "Generic IO", "id": CATEGORY_GENERIC},
        {"name": "Temperature Sensor", "id": CATEGORY_TEMPERATURE_SENSOR},
        {"name": "Lock", "id": CATEGORY_LOCK},
        {"name": "Thermostat", "id": CATEGORY_THERMOSTAT},
        {"name": "Light sensor", "id": CATEGORY_LIGHT_SENSOR},
        {"name": "UV sensor", "id": CATEGORY_UV_SENSOR},
        {"name": "Humidity sensor", "id": CATEGORY_HUMIDITY_SENSOR},
        {"name": "Power meter", "id": CATEGORY_POWER_METER},
    ],
    "devices": [
        {
            "name": "Ignore 1",
            "altid": "6",
            "id": DEVICE_IGNORE,
            "category": CATEGORY_SWITCH,
            "subcategory": 1,
            "room": 0,
            "parent": 1,
            "armed": "0",
            "armedtripped": "0",
            "configured": "1",
            "batterylevel": "100",
            "commFailure": "0",
            "lasttrip": "1571790666",

def unit_of_measurement(self):
        """Return the unit of measurement of this entity, if any."""

        if self.vera_device.category == veraApi.CATEGORY_TEMPERATURE_SENSOR:
            return self._temperature_units
        if self.vera_device.category == veraApi.CATEGORY_LIGHT_SENSOR:
            return "lx"
        if self.vera_device.category == veraApi.CATEGORY_UV_SENSOR:
            return "level"
        if self.vera_device.category == veraApi.CATEGORY_HUMIDITY_SENSOR:
            return "%"
        if self.vera_device.category == veraApi.CATEGORY_POWER_METER:
            return "watts"

def unit_of_measurement(self):
        """Return the unit of measurement of this entity, if any."""
        import pyvera as veraApi
        if self.vera_device.category == veraApi.CATEGORY_TEMPERATURE_SENSOR:
            return self._temperature_units
        if self.vera_device.category == veraApi.CATEGORY_LIGHT_SENSOR:
            return 'lx'
        if self.vera_device.category == veraApi.CATEGORY_UV_SENSOR:
            return 'level'
        if self.vera_device.category == veraApi.CATEGORY_HUMIDITY_SENSOR:
            return '%'
        if self.vera_device.category == veraApi.CATEGORY_POWER_METER:
            return 'watts'